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A135324 a(n) = Sum_{k=1..phi(n)} k*t(k), where t(k) is the k-th positive integer which is coprime to n and phi(n) is the number of positive integers which are <= n and are coprime to n. 1
1, 1, 5, 7, 30, 11, 91, 50, 120, 64, 385, 76, 650, 191, 354, 372, 1496, 243, 2109, 468, 1081, 795, 3795, 560, 3450, 1336, 3033, 1432, 7714, 692, 9455, 2856, 4595, 3056, 6974, 1836, 16206, 4299, 7766, 3576, 22140, 2126, 25585, 6100, 8922, 7711, 33511 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..47.

FORMULA

a(n) = Sum_{k=1..A000010(n)} k*A126572(n,k). - R. J. Mathar, Jan 30 2008

EXAMPLE

The positive integers that are coprime to 12 and are <= 12 are 1,5,7,11. So a(12) = 1*1 + 2*5 + 3*7 + 4*11 = 1+10+21+44 =76.

MAPLE

A126572 := proc(n, k) local a, i ; a := 1 ; for i from 1 to k do if i = k then RETURN(a) ; fi ; a := a+1 ; while gcd(a, n) <> 1 do a := a+1 ; od; od: end: A135324 := proc(n) add( k*A126572(n, k), k=1..numtheory[phi](n)) ; end: for n from 1 to 80 do printf("%d, ", A135324(n) ) ; od: # R. J. Mathar, Jan 30 2008

CROSSREFS

Sequence in context: A171619 A153411 A081630 * A107639 A069688 A158323

Adjacent sequences:  A135321 A135322 A135323 * A135325 A135326 A135327

KEYWORD

nonn

AUTHOR

Leroy Quet, Dec 06 2007

EXTENSIONS

More terms from R. J. Mathar, Jan 30 2008

STATUS

approved

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Last modified April 18 22:08 EDT 2019. Contains 322237 sequences. (Running on oeis4.)